Steel titan finally won battle for rival Arcelor in June. $34 billion merger created industry behemoth that now accounts for more than 10% of world's production, dwarfs rivals. Mittal owns 44.7% of combined Arcelor Mittal; recently named its chief executive.

Methodology: Unlike Forbes' Billionaires list, this ranking has been broadened to include family fortunes. For instance, Tulsi Tanti's $5.9 billion fortune represents his family's entire 70% stake in Suzlon Energy, not just his personal 30% stake. For people with fortunes in publicly traded companies, net worths were calculated using Nov. 6 market prices and exchange rates. Privately held companies are valued by coupling estimates of revenues or profits (or, in some cases, company-provided numbers) to prevailing ratios for similar publicly traded companies.